The invention relates in general to gaskets for providing a seal between two mating components and in particular to an improved formula for a curable coating applied to gaskets for sealing purposes and an improved method for curing the coating.
Gaskets are well known articles which are adapted to provide a leak-proof seal between two mating components. Typically, the two components are formed having mating surfaces which are disposed adjacent to one another during use. During assembly of the components, a gasket is placed between the mating surfaces. Such gaskets are typically formed having a plurality of ports or openings for accommodating the passage of various gases and fluids between the joined components. Bolts or similar means are utilized to connect the two components together and compress the gasket between the mating surfaces. When compressed in this manner the gasket effects a relatively leak-proof seal between the two components.
In order to enhance the seal, rigid gaskets are frequently coated with a resilient material. The resilient material may be applied to the gasket to form a covering layer, or it may be formed in beads surrounding the various openings formed through the gasket and along the perimeter of the gasket itself. As the bolts are tightened, the gasket and the resilient material are compressed between the mating parts. Such compression initially causes the resilient material to be compressed into the gasket material to form a seal between the parts being joined. Further compression causes the remainder of the gasket to be compressed between the pans. Thus, a tight sea is formed between the mating parts.
Typically, the resilient material is applied to both sides of the gasket, but it may be on only one side. A compressible elastomeric material, such as a nitrile epoxy copolymer or a silicone polymer, is often used for the coating. A number of processes exist for applying the resilient material to the gasket, including silk screening and printing. Often, a solvent is added to the resilient material to reduce its viscosity as an aid in the application process.
Once the resilient material is applied to the gasket, the coated gasket is cured to solidify the material. Curing also optimizes the physical and chemical properties of the coating as well as assuring adhesion of the coating to the gasket core. Curing is usually accomplished by heating the coated gasket in an oven. The heating, in addition to chemically curing the coating, causes the solvent to evaporate, thereby releasing solvent fumes into the environment. Certain types of gasket coatings can also be cured by exposure to other forms of radiant energy, such as ultraviolet light waves.